The Spaniard had visited doctors in Barcelona on Monday and subsequently made the final decision not to play both upcoming events, the ATP 500 tournament in Beijing and the Masters 1000 event in Shanghai.

"While the annoyances on my knee are nothing new, we have decided together with my medical and technical team not to participate in the Asian tour to recover the knee the way we have always done," Nadal said on Wednesday.

"I am sorry I can't be with all the fans in China and with the organisers of the Beijing and Shanghai tournaments that have always had a great relationship with me and my team."

Nadal after defeating Kyrgios to win the 2017 China Open title. (Photo by Lintao Zhang/Getty Images)

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Nadal enjoyed a solid Asian swing last year, defeating Nick Kyrgios to win the China Open title and following it up with a runner-up finish in Shanghai, where he lost to arch-rival Roger Federer. The 17-time major champion will drop 1100 points earned from both events, which opens the way for resurgent Novak Djokovic (who isn't defending any points for the rest of the season) to regain the number one ranking.

It is uncertain whether the king of clay will be fit enough to play the last Masters event in Paris and season-ending World Tour Finals in London, where he has qualified to feature in the elite 8-man field. Nonetheless, Nadal has enjoyed a stellar 2018 season, highlighted by titles in Barcelona, Rome, Roland Garros and most recently in Toronto.